Dancing makes you agreeable.

Whether you're marching in step with others or slow dancing with your sweetie, moving in sync makes you feel connected to something larger. As a result, you're more willing to cooperate with your partners, according to Scott Wiltermuth, an assistant professor of management and organization at the University of Southern California with two recent papers on the phenomenon, which is called collective effervescence.

Singing synchronizes your heart rate.

When Swedish researchers asked members of a high school choir to hum, sing a hymn, and chant a mantra together, they found that the singers' heart rates increased and decreased at the same time. "Songs with long phrases require controlled breathing," said Bjorn Vickhoff, the lead researcher. "The heart rate decreases when breathing out and increases during inhalation. We already know that singing synchronizes muscle and brain activity," he added. "Now we know that this synchrony also applies to the heart."

Laughter helps you bond.

Why is it we get an uncontrollable urge to smile or laugh when we see or hear others chuckling? In a study by Sophie Scott, a neuroscientist at the University College in London, volunteers heard a recording of laughter. The sound triggered activity in the their premotor cortical cortex, the area of the brain that controls the movement of the face, essentially priming them to break out in a smile. "This response provides a way of mirroring the behavior of others," said Scott. "That could play an important role in building strong bonds between individuals in a group."

Yawning helps us show empathy.

Around age four we learn contagious yawning as a way to demonstrate to others that we care, according to Molly Helt, a graduate student in clinical psychology at the University of Connecticut. "Emotional contagion seems to be a primal instinct that binds us together. Yawning may be part of that," she added. Helt thinks that contagious yawns might diffuse stress after a period of high alert. Interestingly, the behavior only exists in humans, chimps, and possibly dogs.